I keep meaning to ask this question. As some of you may remember I sent my camera in a few months back because of over and under exposed photos on auto settings basically. It came back stating that it worked fine for them and that I needed to use different batteries.

I was using it yesterday and it acted up againfor the first time since coming back. The battery indicator was showing full charge. I hadn't charged the batteries since 8/23 and had taken 260 photos since then.On AV it gave me the following shot on a bright sunny day. I removed the batteries and put them back in then continued on and it worked fine. I took another 65 photos over the course of the day before it acted up again. So, I'm sure they are right and it's the batteries. They get low and just can't handle the camera I guess. I don't think the camera ever did this when I was using the CRV3's.

So, I'm curious. What batteries does everyone that has the K100D use. I've had the camera for 13 months.Probably the first6 months I used CRV3's exclusively. Then, I finally broke down and bought a battery charger and 4 sets of the Rayovac Hybrid batteries. Pentax seems to think it's the Rayovac's causing the problems. They are 2100 mAh NiMH's. They say to use at least 2500 mAh. (This is from memory. I'll post their exact comments later when I can find it.) They recommended using CRV3's (I know not rechargeables)as the best option.

Before I go back to CRV3's or go out and purchase some higher mAh's I thought I'd ask here what others have had success with in this camera. I carry my camera with me everywhere and will usually photograph things a few times a week. So, the batteries don't sit idly for long periods of time. (Although, this last stretch they did as I've been too busy lately.)

I started off with two sets of 2500 mAh tecxus brand rechargeables. For the first 4-5 recharge cycles they were OK, gave me several hundreds of photos. But soon they deteriorated to giving me minutes of fun after being fully charged. In a mini torch they lit the lamp for hours though so it must be something with low voltage rather than few electrones left to run their race from + to -.

I bought two new sets, now GP 2700 mAh, and the difference is striking. They sit in the camera for a week or three (and I use my camera a lot), and the spare set is OK after lying in the bag for as long. Never need to check the batteries before I leave home, if the ones in the camera run out in the middle of shooting I can rely on the spare set.

I still use the same charger that I bought with the crappy tecxus batteries. Others have experienced that the charger matters as well.

I have a DS, I think it might be a little less power consuming since it doesn't have the SR. But that should be on the margin of matters.

That's just it with the -2 compensation. I had it set to generically "0" in the menu. The camera is what set it to -2 when I had it set on AV. I had set the aperature to f13 and the camera selected everything else.

I've attached a photo taken a while back in full auto. Again, it was a bright sunny day.

And, then this is the photo after I took the batteries out and put them back in taken in manual mode. This is actually a little brighter than the actual image looked to my eyes.

I don't know much about electronics, but seems they are right in stating that the batteries don't have enough power to run the camera. I know that not too long after both of these shots I had to put new batteries in.

I have had the camera for just about a year. The original AAs lasted 10 frames. So while looking at what batteries to use I picked up some CRV3s. Now after 2384 frames, I am about partway through my third set, so it appears that I am getting about 700 to 900 frames (not using a lot of flash) per set. I got too lazy in going to look for a better replacement - so far, I am happy with the Duracell Ultra CRV3s.

I figured that someone here, would hit upon the perfect brand / type of rechargable combination that would work first time - every time without any problems.... still waiting.

I use a couple of sets of Sanyo 2500rechargeables. I bought a charger and 6 batteries at Costco and have hadpretty good luck with them. I've actually bought a second one when I had both the DS and K100, which gave me two chargers and 3 sets of batteries between 2 cameras. I had bought a set of 2500 batteries (think they were Duracell) that were horrible - wouldn't hold a charge very long at all. I have better luck with the Sanyos when I'm using the K100 as my primary camera - the batteries in the camera will run out before the spares lose their charge (when it's backing up the K10, I don't use it enough to use it enough to use the batteries faster than their shelf discharge rate - which means the second set is usually just as dead as the ones in the camera). I had been thinking of buying some CRV3 for the K100 when I was using it only as a back-up.

Your situation with the camera changing the Ev setting on its own and then switching it back when you took the batteries out is certainly bizzarre.

I've used Sanyo Eneloops since I got the camera and have been very pleased with them.

I personally doubt that your problems are battery related though, at least not based on what little I'm seeing about the issue. Your dark photo has a -2 exposure compensation, and the bright one was taken using manual settings so neither indicates that the camera is not capturing what it should be, only that the settings aren't what you want them to be.

Without knowing much about your experience with the camera, I'd have to guess the problems are either user error or some kind of software problem in the camera. If someone was to tell me that they had erratic problems with getting pictures that are underexposed as well as overexposed, my first suspicion would be that the shooting mode was set to auto-bracket. This would alternate between normal exposure, underexposed, and overexposed. Without seeing a continuous series of shots that you've taken where you've seen the problem though, I couldn't really be sure this was the cause.

If it's software in the camera that is causing the problem, I'm not sure what you could do about that. I'd try resetting all the custom settings, but if the problem is in the firmware I'm not sure what you could do about that.

Finally, and I'm not sure this relates, but I've had a problem of my own with one of my old, manual focus lenses where on occasion, every other shot would be taken where the camera would not stop down the lens. This caused every other photo to be overexposed. Since I didn't see any lens info in the Exif of your bright photo other than focal length, I guessed you might be using a manual lens and perhaps it has the same problem.